Data storage devices store digitally encoded information on discs. Heads read from or write data to discs which are supported for rotation relative to a base chassis by a spindle motor or drive. Heads include transducer elements, such as magnetoresistive, magneto-optical or inductive elements for read or write operations. An actuator assembly moves the head relative to select data tracks on the disc to read or write data to the disc surface or media. The head is positioned relative to tracks via a servo control system based upon servo information or patterns on a rotating disc or discs. For example, servo patterns or information can be encoded on a disc or discs between data sectors of each track of a disc “embedded servo information” or on a surface of a dedicated disc or “dedicated servo”.
Servo information or patterns are pre-recorded or written during manufacture of the data storage device for example, via a dedicated servo track writing apparatus. Multi-disc servo track writers are used to prerecord servo patterns or information to a plurality of discs for high-density recording. Recording density is increasing requiring more accurate servo control feedback which is limited by alignment of the recorded servo patterns or information on the disc or discs. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.